Saturday, November 22, 2008

Cask Ale

Consumers are quite familiar with the common serving methods for beer, both mass-produced and craft. Beer may be served either from a large keg via a tap in the wall or it may be put into smaller containers, either colored glass bottles or aluminum cans. But most consumers in the United States are woefully unaware of a third, unique style of service that gives rise to a world of different treatments: cask ale.

A cask is nothing more than a small traditional wooden storage vessel, still used today for aging whiskey and other spirits. Taking its name from the historical container, cask ales are more accurately described as cask-conditioned ales and very often as real ales, as their methods are steeped in tradition long eschewed by modern commercial breweries. The beers are fermented and then packaged into the cask (although the process can use modern metal kegs as well), at which time a small dose of yeast is added before it is sealed.

The resulting beer is a naturally fermented, unpasteurized ale that has striking differences to the same brand available in bottles, cans or kegs. Cask ale is actually “unfinished” beer, as the late dose of yeast provides a natural and ongoing late fermentation and the lack of pasteurization means the ale is still “alive.” Yes, with cask ale you will most likely be drinking what few living yeast cells are left, depending on the age of the cask—and this is just fine.

What should you expect from a cask serving? First, the beer is not propelled through the lines using gas pressure on the keg, as most taps are served (a blend of carbon dioxide and nitrogen aptly named beer gas). The beer must be laboriously hand-pumped using what is known as a beer engine, a simple mechanical piston with a thick handle used to draw the beer from the cask that is the historical and traditional method that beers have been served.

Other differences arise from the nature of the late fermentation of the product. The beer is generally served at “cellar temperature,” or a temperature slightly cooler than ambient and closer to that found in underground cellars used for aging. The beer is also left unfiltered, so a glass of cask ale may be cloudy and turbid. Keep in mind that nothing is wrong with this style of service; a cool (neither warm nor ice-cold) and hazy pint of beer is normal for cask ales.

What you taste is something fuller, richer, softer and more subtle than the same product poured from a wall tap. The beer is naturally carbonated by the remaining yeast instead of force-carbonated by gas pressure, so the mouthfeel is generally softer and less effervescent. Because it is unfiltered and unpasteurized, different delicate flavors are present that are tied to the yeast and other compounds usually removed by sterile filters and heat.

The tradeoff with a dramatic rise in the quality of flavor in cask service is a great reduction in shelf-life. In this sense, cask ale has much in common with freshly baked bread or fruits and vegetables. Pasteurization is a preservative measure, and the lifetime of a cask of beer is generally listed in terms of days or a couple of weeks. Left in the cask too long, the beer can sour through the continued action of the live yeast and other microorganisms.

Tragically, cask ale is a rare species as its short shelf-life and unfamiliar qualities are frowned upon by mass consumers and profit-driven retailers. Long enjoyed as the standard product in the United Kingdom, organizations such as the Campaign for Real Ale (CAMRA) work hard to keep cask ale alive and popular. If you see such a device in the States, enjoy it for the rarity it is here.

1 comment:


Most beer casks in use are stainless steel.